Heating press and method for vulcanizing a vehicle tire in said heating press under vacuum

ABSTRACT

A heating press ( 1 ) for vulcanizing a vehicle tire under a vacuum,
         having a heating press upper part ( 3 ) and a heating press lower part ( 6 ), wherein the heating press upper part ( 3 ) has a hood upper part ( 4 ) mounted thereon and a container ( 2 ), which contains mold parts ( 16, 18, 21 ) of a segmented vulcanizing mold, in this hood upper part ( 4 ), wherein the hood upper part ( 4 ) has a first circular ring ( 23 ), which is arranged fixedly on the heating press upper part ( 3 ), and a second circular ring ( 24 ), which adjoins this first circular ring coaxially in an axial direction and can be telescopically retracted and extended out over the first circular ring ( 23 ) in an axial direction P 1,      wherein vacuum-tight seals ( 5, 9 ) are arranged between the two circular rings ( 23, 24 ) and between the second circular ring ( 24 ) and the heating press lower part ( 6 ),   wherein, after a first partial stroke (TH 1 ), the hood upper part ( 3 ) can be moved in such a way that it rests on the heating press lower part ( 6 ) by way of the extended second circular ring ( 24 ), and the interior space of the hood ( 12 ) can be closed in a vacuum-tight manner by the seals ( 5, 9 ) although the vulcanizing mold is still open in an air-permeable manner and   wherein a pump ( 10 ) and a vacuum tank ( 11 ), by means of which a vacuum can be generated in the interior space of the hood ( 12 ) after the first partial stroke (TH 1 ), are provided,   wherein, after a second partial stroke (TH 2 ), the hood upper part ( 3 ) can be moved in such a way that the second circular ring ( 24 ) can be retracted out further over the first circular ring ( 23 ) and the vulcanizing mold can be completely closed under vacuum conditions in the interior space of the hood ( 12 ).

The invention relates to a heating press for vulcanizing a vehicle tire,having a heating press upper part and a heating press lower part,wherein the heating press upper part has a hood upper part mountedthereon and a container, which contains a mold part of a vulcanizingmold, in this hood upper part, wherein the heating press upper part andthe heating press lower part are connected to the container such that,when the heating press upper part is being lowered through a totalstroke that takes place in an axial direction, during which total strokethe open end of the hood upper part moves onto the heating press lowerpart, the mold parts of the vulcanizing mold can be closed in the radialdirection.

The invention furthermore relates to a method for vulcanizing a greentire in this abovementioned heating press.

The above-described heating press is a standard heating press forvulcanizing vehicle tires under atmospheric conditions.

The heating press comprises a so-called container which comprises theactual segmented vulcanizing mold with the mold segments and sidewallshells and bead rings, which mold the tire. Furthermore, heatingchambers are provided for controlling the temperature of the moldingparts. During the vulcanization, the container is surrounded by a closedhood which, in the prior art, serves primarily for temperatureinsulation during the vulcanization.

In order to as far as possible avoid defects on the tire surface, theair between the surface of the green tire and the surface of the moldfaces must be removed. For this purpose, it is generally known for 1000to 5000 ventilation valves to be provided in the mold faces of the moldparts. By means of these ventilation valves, the air from the moldcavity is discharged radially and axially outward through ventilationchannels. However, the mold parts of a new vulcanizing mold have to beequipped with these valves. Furthermore, these valves tend to becomedirty owing to rubber that ingresses from the tire for vulcanization,such that said valves have to be exchanged or cleaned, which requiresgreat outlay.

The invention is based on the object of providing a heating press forvulcanizing a vehicle tire under a vacuum, with which vehicle tires canbe reliably vulcanized without the need for ventilation valves in thevulcanizing mold. It is likewise an object of the invention to provide amethod for vulcanizing a vehicle tire in an efficient manner in terms oftime.

The object is achieved in relation to the heating press in that

-   -   the hood upper part has a first circular ring, which is arranged        fixedly on the heating press upper part, and a second circular        ring, which adjoins this first circular ring in an axial        direction and can be displaced out over the first circular ring        in an axial direction P1,    -   vacuum-tight seals are arranged between the two circular rings        and between the second circular ring and the heating press lower        part,    -   the total stroke (GH) can be traveled in a manner composed of a        first partial stroke (TH₁) and a second partial stroke (TH₂),    -   after the first partial stroke, the hood upper part can be moved        in such a way that it rests on the heating press lower part by        way of the second circular ring, and the interior space of the        hood upper part is closed in a vacuum-tight manner by the seals        although the vulcanizing mold is still open in an air-permeable        manner and,    -   in order to generate a vacuum in the interior space of the hood        before completely closing the vulcanizing mold, a pump and a        vacuum tank, by means of which a vacuum can be generated in the        interior space of the hood after the first partial stroke, are        provided, wherein the vacuum tank and the pump are connected to        the interior space of the hood, and wherein the vacuum tank and        the pump are connected to one another, and,    -   after the second partial stroke, the hood upper part can be        moved in such a way that the second circular ring can be        displaced out further in relation to the first circular ring and        the vulcanizing mold can be closed in an airtight manner under        vacuum conditions in the interior space of the hood.

The vacuum that can be obtained after the first partial stroke serves toremove the air from the not yet completely closed vulcanizing mold, inparticular to remove the air between the outer surface of the tire andthe mold faces of the shaping parts of the vulcanizing mold, in order,after the second partial stroke, which makes it possible to completelyclose the vulcanizing mold, to be able to manufacture the tire forvulcanization with high quality and without defects.

The term “circular ring” has the meaning of “cylinder with approximatelycircular-ring-shaped cross section”.

It is furthermore essential that the vulcanizing mold itself has noventilation means for ventilating the mold cavity. The 1000 to 5000ventilation valves arranged in the vulcanizing mold in the prior art,through which ventilation valves the air from the mold cavity isdischarged radially to the outside, are omitted by virtue of thevulcanization being performed under a vacuum. In this way,post-processing of the rubber flash that is formed on the tire by theventilation means is no longer necessary, and the exchange and/orcleaning of ventilation valves that are no longer functional can bedispensed with. These are time-consuming and expensive. Furthermore, byvirtue of the vulcanization being performed under a vacuum, thevulcanized tire takes on an external form which is absolutely free fromdefects and is thus of perfect appearance.

In addition, it is essential according to the invention for the hoodupper part to have two circular rings, the first circular ring of whichis arranged fixedly on the heating press upper part and the secondcircular ring of which can be telescopically displaced out over thefirst circular ring. This has the effect that—with both circular ringsof the hood upper part having been extended and the hood having beenlowered onto the heating press lower part—a vacuum-tight interior spaceof the hood around the container can be achieved by means of the sealsprovided, although the vulcanizing mold is not yet completely closed. Itis explicitly the intention that no modifications with regard tomeasures for providing vacuum-tightness be made to the container or tothe vulcanizing mold itself.

The term “vacuum” refers to air pressure in the range from 950 mbar(abs) to 0.1 mbar (abs).

The ring seal preferably has a round, polygonal or flat cross section.

It is expedient if a hydraulic, pneumatic or electric actuator, whichcan move the second circular ring of the hood upper part in an axialdirection, is provided.

A hood lower part in the form of a third circular ring is preferablyarranged on the heating press lower part of the heating press. In thatcase, depending on the relative size of the diameter of the secondcircular ring of the hood upper part to the diameter of the thirdcircular ring of the hood lower part, there is a different arrangementof the sealing ring between the second circular ring of the hood upperpart and the third circular ring of the hood lower part.

If the diameter of the second circular ring of the hood upper part isslightly greater than the diameter of the third circular ring of thehood lower part, either the third circular ring has a vacuum-tight sealaround the periphery on its outer side or the second circular ring has avacuum-tight seal around the periphery on its inner side. The seal sealsoff the small intermediate space between the second circular ring of thehood upper part and the third circular ring of the hood lower part whenthe second circular ring rests on the hood lower part. This is the casewhen the heating press has traveled at least through the first partialstroke (TH₁) of the total stroke (GH).

If the diameter of the second circular ring of the hood upper part isexactly the same size as the

diameter of the third circular ring of the hood lower part, either thethird circular ring has a vacuum-tight seal around the periphery on itsupper side or the second circular ring has a vacuum-tight seal aroundthe periphery on its lower side. The seal then provides sealing if thesecond circular ring rests on the third circular ring of the hood lowerpart. This is the case when the heating press has traveled at leastthrough the first partial stroke (TH₁) of the total stroke (GH).

If the diameter of the second circular ring of the hood upper part isslightly less than the diameter of the third circular ring of the hoodlower part, either the third circular ring has a vacuum-tight sealaround the periphery on its inner side or the second circular ring has avacuum-tight seal around the periphery on its outer side. The seal sealsoff the small intermediate space between the second circular ring of thehood upper part and the third circular ring of the hood lower part whenthe second circular ring rests on the hood lower part. This is the casewhen the heating press has traveled at least through the first partialstroke (TH₁) of the total stroke (GH).

In a certain embodiment of the invention, a hood lower part in the formof a third circular ring is arranged on the heating press lower part,wherein the first circular ring of the hood upper part and the thirdcircular ring of the hood lower part have the same inside diameter andthe same outside diameter and are arranged in line with one another inthe heating press. This results in very reliable sealing of the hoodinterior space, in particular when a sealing ring is also arranged onthe upper end of the third circular ring or on the lower end of thefirst circular ring.

In this embodiment, it is then preferably the case that the thirdsealing ring also has a vacuum-tight seal around the periphery on itsouter side that provides sealing between the second circular ring of thehood upper part and the third circular ring of the hood lower part whenthe second circular ring rests on the hood lower part. This is the casewhen the heating press has traveled at least through the first partialstroke (TH₁) of the total stroke (GH).

It is expedient if the seals are ring seals, and at least one ring sealis arranged in the lower region of the hood upper part and at least onefurther ring seal is arranged in the upper region of the hood lowerpart. The vacuum is generated by ensuring that the first and the secondcircular ring of the hood upper part and the third circular ring of thehood lower part are sealed off with respect to one another in each caseby at least one ring seal.

It is expedient for reliable sealing if the ring seals are arranged incircular-ring-shaped grooves, wherein the diameter of the ring seals isslightly greater than the depth of the grooves. Slightly greater meansthat the seal, when installed into the groove and in the sealing state,is compressed by at most 40% in relation to the compression-freegeometry of the seal. Through the exact design of the groove in relationto the seal geometry, damage to the seal(s) as a result of the(relative) movements of the two or three circular rings is prevented,and durability is improved.

In one embodiment of the invention, the ring seals consist of solidmaterial. The solid material may consist of one or more materials thatare known for seals, such as FKM or FFKM. These seals are inexpensiveand easy to handle.

In another embodiment of the invention, the ring seals are hoses ofvariable diameter. This has the advantage that less load is exerted onthe ring seal by relative movements between circular rings of the hood,and the diameter of said ring seal is enlarged only when the sealingaction is necessary.

It is advantageous if the ring seals are differentially inflated doublering seals. This has the advantage that any leakage can be compensatedwith low levels of pump power.

The vacuum-tight sealing can also be effected between the first circularring and the second circular ring of the hood upper part by means of anelastically extensible, vacuum-tight rubber sleeve. This is secured in acircular shape on the inside of the lower part of each of the twocircular rings.

In order to improve mechanical support of the hood parts, or thecircular rings, against one another, it is expedient if sliding bandscomposed of wear-resistant high-temperature polymer, for example ofPEEK, are arranged in the hood parts, or on the circular rings, in theregion above and/or below the ring seals.

It is expedient if the vacuum tank has a volume that is approximately 5to 10 times greater than the volume of the closed hood (including mold,container, green tire, heating bellows). It is hereby ensured that avacuum can be reliably generated in the hood. Furthermore, the timerequired for the generation of the required vacuum is significantlyreduced. This may take place during the course of the normal loading andunloading process.

With regard to the method with an abovementioned heating press, theinvention is achieved in that the following steps are performed insuccession:

-   -   a) loading the open heating press by inserting the green tire        for vulcanization into the container, wherein the second        circular ring of the hood upper part is retracted out over the        first circular ring,    -   b) moving the heating press upper part through the first partial        stroke, extending the second circular ring toward the heating        press lower part until it rests on the heating press lower part,        in order to obtain a closed hood interior space, while the        vulcanizing mold is only closed to some extent,    -   c) only if the ring seals are a hose of variable diameter:        inflating the circular-ring-shaped hose seal in order to seal        off the hood in vacuum-tight fashion,    -   d) opening the connection between the vacuum tank and the hood        interior space in order to generate a partial vacuum, by way of        pressure equalization between the vacuum tank and the hood        interior space, in the hood interior space that has been closed        in a vacuum-tight manner,    -   e) when the partial vacuum is obtained in the hood interior        space: closing the connection between the vacuum tank and the        hood, opening the connection between the hood interior space and        the pump, and pumping the remaining air out of the hood interior        space in order to generate the vacuum,    -   f) moving the heating press upper part through the second        partial stroke, during which the second circular ring is        retracted out over the first circular ring, with the result that        the vulcanizing mold is completely closed, and subsequently        closing the connection between the hood interior space and the        pump,    -   g) vulcanizing the green tire and opening the connection between        the pump and the vacuum tank and generating a vacuum in the        vacuum tank, wherein the connection of the pump to the hood        interior space and the connection of the vacuum tank to the hood        interior space are each closed,    -   h) opening the heating press and unloading the fully vulcanized        tire, and repeating the steps a)-h) in order to vulcanize each        further tire.

The tire vulcanization can be performed in an efficient manner in termsof time by way of the above-stated method. During the vulcanization of afirst tire, the vacuum tank is already prepared for the generation ofthe vacuum in the hood for the vulcanization of a second, subsequenttire, such that a vacuum can be generated in the hood within anextremely short time.

It is advantageous if, to facilitate step h), this is preceded by afurther valve arranged in the hood being opened in order to deplete thevacuum in the hood and subsequently being closed again.

An exemplary embodiment of a heating press and the method for vacuumvulcanization of a pneumatic vehicle tire, together with furtheradvantages, will be described on the basis of the following schematicFIGS. 1 to 4 . In the figures:

FIG. 1 shows a first embodiment of a heating press according to theinvention with a container in the open state;

FIG. 2 shows the heating press of FIG. 1 in the closing phase after afirst partial stroke;

FIG. 3 shows the heating press of FIG. 1 and of FIG. 2 in the closedstate after a second partial stroke;

FIG. 4 shows a second embodiment of a heating press according to theinvention with a container in the open state;

FIG. 5 shows the heating press of FIG. 4 in the closing phase after afirst partial stroke;

FIG. 6 shows the heating press of FIG. 4 and of FIG. 5 in the closedstate after a second partial stroke;

FIG. 7 shows a third embodiment of a heating press according to theinvention with a container in the open state;

FIG. 8 shows the heating press of FIG. 7 in the closing phase after afirst partial stroke;

FIG. 9 shows the heating press of FIG. 7 and of FIG. 8 in the closedstate after a second partial stroke;

FIG. 10 shows a fourth embodiment of a heating press according to theinvention with a container in the open state;

FIG. 11 shows the heating press of FIG. 10 in the closing phase after afirst partial stroke.

FIG. 1 shows a first embodiment of a heating press 1 according to theinvention with a container 2 in the open state. The green tire can beplaced into the heating press 1.

The heating press 1 comprises a heating press upper part 3, which isconnected to the hood upper part 4, and a heating press lower part 6,which is connected to the hood lower part 7 and has the correspondingmechanisms for positioning the tire for vulcanization, for actuating theconstituent parts of the vulcanizing mold, for introducing the heatingmedia, and for removing the fully vulcanized tire. During thevulcanization operation, the container 2 is enclosed by the two-parthood 4, 7. The hood upper part 4 has a first and a second circular ring23, 24, wherein the second circular ring 24 is provided with a greaterdiameter than the first circular ring 23. The second circular ring 24can be telescopically retracted and extended on the first circular ring23 in an axial direction P1 by means of an actuator 26. The hood lowerpart 7 has a third circular ring. The third circular ring 7 and thefirst circular ring 23 of the hood upper part 3 have the same insidediameter and the same outside diameter and are arranged with their endfaces in line in the heating press 1. The diameter of the secondcircular ring 24 of the hood upper part 4 is slightly greater than thediameter of the third circular ring 7 of the hood lower part.

A “central mechanism” 8 is provided. This is likewise charged withseals—to the extent necessary—in order to establish vacuum-tightnessbetween the central mechanism and the heating press upper and lowerparts. A heating bellows (not illustrated) that can be placed into thegreen tire (not illustrated) is fastened to the central mechanism 8.Furthermore, nozzles (not illustrated) are arranged on the centralmechanism 8, through which nozzles a heating medium can be introducedinto the heating bellows (not illustrated).

The hood upper part 4 and the hood lower part 7 are airtight, orvacuum-tight, and in the closed state form a vacuum-tight hood interiorspace 12. To that end, ring seals 5, 9 are provided. A ring seal 9 isarranged between the first and the second circular ring 23, 24 in agroove 25, which is arranged in the first circular ring 23 and faces thesecond circular ring 24, for an airtight hood upper part 3. Similarly, aring seal 9 is arranged around the periphery in a groove 25,corresponding to that in the first circular ring 23, in the thirdcircular ring 7 on its outer side. A further horizontal ring seal 5 isarranged in line with the second circular ring 24 in a groove 25 whichis open toward the heating press upper part 3. Therefore, the closedhood is airtight at the joints between the hood upper part 3 and thehood lower part 7, and between the first and the second circular ring23, 24. The ring seal 5, 9 is a hose of variable diameter. The diameterof the ring seal 5, 9 is slightly greater than the depth 27 of thegroove 25.

A vacuum can be generated in the hood interior space (=interior space ofthe hood) 12 by means of a pump 10 and a vacuum tank 11, wherein thevacuum tank 11 and the pump 10 are connected to the interior space 12 ofthe hood, and wherein the vacuum tank 11 and the pump 10 are connectedto one another. By virtue of a vacuum being provided in the hoodinterior space 12, in particular during the molding and thevulcanization of the tire, conventional ventilation valves arranged inthe mold face of the vulcanizing mold are omitted entirely.

The container 2 is a conventional container 2 that is already known inthe prior art.

The container 2 contains the segmented vulcanizing mold with a lowerheating plate 13, a lower sidewall shell 14, an upper heating plate 15,an upper sidewall shell 16, a lower bead ring 17 and an upper bead ring18. Those constituent parts of the vulcanizing mold that are moved in avertical (=axial) direction (arrow P1) for the purposes of opening andclosing include the segment ring 19, composed of seven to nine segmentshoes 20, and the profile/mold segments 21 fastened thereto and also theupper sidewall shell 16 with the upper bead ring 18. The segment shoes20 are moved apart radially, in the direction of the arrow P2, to closeand open the vulcanization mold. On the upper heating plate 15, there isarranged a closing ring 22 which has a beveled inner surface whichinteracts with beveled outer surfaces of the segment shoes 20 of thesegment ring 19 such that, during the closing of the vulcanizing mold,the segment shoes 20 are moved together in a radial direction to formthe closed segment ring 19. In the lower heating plate 13, the upperheating plate 15 and in the closing ring 22, there are incorporatedheating chambers into which at least one heating medium, in particularsaturated steam (water vapor), is introduced for the vulcanization ofthe tire. In this way, the green tire (not illustrated) is heated fromthe outside via the segment shoes 20, the sidewall shells 14, 16 and thebead rings 17, 18, such that this heating is commonly referred to asexternal heating.

A conventional heating bellows (not illustrated) is provided in a knownmanner and is filled with at least one pressurized heating medium inorder to center the green tire in the mold from the inside, wherein theheating bellows is brought into a toroidal shape conforming to a tire.Since the green tire is heated by means of the heating bellows from theinside, this type of heating is referred to as internal heating.

In FIG. 1 , the heating press 1 is open, with the second circular ring24 of the hood upper part 3 having been telescopically retracted overthe first circular ring 23. The green tire can be placed into thecontainer 2.

FIG. 2 illustrates the heating press 1 of FIG. 1 in the closing phaseafter a first partial stroke TH₁.

The heating press upper part 3 is moved through the first partial strokeTH₁ and the second circular ring 24 is extended toward the heating presslower part 7, with the result that it rests on the heating press lowerpart 7 in the region of the horizontal ring seal 5 and overlaps thethird circular ring 7 in the region of the ring seal 9. The ring seal 9seals off the small intermediate space between the second circular ring24 of the hood upper part 4 and the third circular ring 7 of the hoodlower part when the second circular ring 24 rests on the hood lowerpart. A closed, vacuum-tight hood interior space 12 is obtained, whilethe vulcanization mold is closed only to some extent. If the ring seals5, 9 are a hose of variable diameter, they are inflated in order to sealoff the hood 4, 7 in a vacuum-tight manner. The connection between thevacuum tank 11 and the hood interior space 12 is opened in order togenerate a partial vacuum, by way of pressure equalization between thevacuum tank 11 and the hood interior space 12, in the hood interiorspace 12 that has been closed in a vacuum-tight manner. When the partialvacuum has been generated in the hood interior space 12, the connectionbetween the vacuum tank 11 and the hood 4, 7 is closed, the connectionbetween the hood interior space 12 and the pump 10 is opened and theremaining air is pumped out of the hood interior space 12 to generatethe vacuum.

FIG. 3 shows the heating press of FIG. 1 and of FIG. 2 in the closedstate after a second partial stroke TH₂. After a vacuum has beengenerated in the interior space 12 of the closed hood 4, 7 of FIG. 2 ,the performance of a second partial stroke TH₂, during which the secondcircular ring 24 is retracted out over the first circular ring 23, thencauses the vulcanizing mold, which has been evacuated of air, to becompletely closed and the connection between the vacuum tank 11 and thehood 4, 7 to be closed.

Then, the connection between the hood interior space 12 and the pump 10is closed. The green tire is vulcanized.

The sum of the first partial stroke TH1 and the second partial strokeTH₂ yields the total stroke GH. The tire is vulcanized. In the case of apassenger motor vehicle tire, the vulcanization thereof takesapproximately 15 minutes. During this time, the connection between pump10 and vacuum tank 11 is opened in order to generate a vacuum in thevacuum tank 11, wherein the connection of the pump 10 to the hood 4, 7and the connection of the vacuum tank 11 to the hood 4, 7 are eachclosed. After the vulcanization of the tire is complete, the volume ofthe hood interior space 12 is aerated via a valve (not illustrated), andthe heating press 1 is opened in order to unload the fully vulcanizedtire from the container 2 having the vulcanizing mold. To that end, thehood upper part 4 is first of all advanced, the second circular ring 24is retracted out over the first circular ring 23, and the profilesegments 21 are moved outward in a radial direction P2 at the same time.The tire is released.

In the following further embodiments of a heating press 1 according tothe invention that are shown in FIGS. 4 to 11 , almost all the elementsand functions have the same configuration as in the first embodiment.Differences exist only in terms of the relative size of the diameter ofthe second circular ring 24 of the hood upper part 4 to the diameter ofthe third circular ring 7 of the hood lower part. Therefore, merely adifferent arrangement of the sealing ring 9 between the second circularring 24 of the hood upper part 4 and the third circular ring 7 of thehood lower part will be discussed.

Therefore, merely the first circular ring 23 and the second circularring 24 of the hood upper part and the third circular ring 7 of the hoodlower part, and the vacuum-tight seals between the two circular rings23, 24 of the hood upper part and between the second circular ring 24 ofthe hood upper part and the third circular ring of the hood lower part,are provided with reference signs.

All other elements of the heating press are not explicitly provided withreference signs and the means, connected to the heating press, forgenerating a vacuum in the interior space of the hood of the heatingpress, such as the pump 10, the vacuum tank 11 and associated lines andvalves, are not shown in FIGS. 4 to 11 for the sake of simplicity, eventhough they are present in the heating presses shown in the same way asin FIGS. 1 to 3 . The elements of the heating press that are notprovided with reference signs and the means, which are not shown, forgenerating a vacuum in the interior space of the hood of the heatingpress have already been described in connection with the firstembodiment, as have their function and the overall mode of operation ofa heating press according to the invention.

FIG. 4 shows a second embodiment of a heating press according to theinvention with a container 2 in the open state. The hood upper part hasa first and a second circular ring 23, 24, wherein the second circularring 24 is provided with a greater diameter than the first circular ring23. The second circular ring 24 can be telescopically retracted andextended on the first circular ring 23 in an axial direction P1 by meansof an actuator 26. The hood lower part 7 has a third circular ring. Thediameter of the second circular ring 24 of the hood upper part isexactly the same size as the diameter of the third circular ring 7 ofthe hood lower part.

The hood upper part 4 and the hood lower part 7 are airtight, orvacuum-tight, and in the closed state form a vacuum-tight hood interiorspace 12. To that end, ring seals 9 are provided. A ring seal 9 isarranged between the first and the second circular ring 23, 24 in agroove 25, which is arranged in the first circular ring 23 and faces thesecond circular ring 24, for an airtight hood upper part 4. Similarly,the third circular ring 23 has a vacuum-tight ring seal 9 around theperiphery at its upper end. Therefore, the closed hood is airtight atthe joints between the hood upper part 4 and the hood lower part 7, andbetween the first and the second circular ring 23, 24. The ring seal 9is a hose of variable diameter. The diameter of the ring seal 9 isslightly greater than the depth 27 of the groove 25 in which it isarranged.

FIG. 5 illustrates the heating press 1 of FIG. 4 in the closing phaseafter a first partial stroke TH₁.

The heating press upper part 3 is moved through the first partial strokeTH₁ and the second circular ring 24 is extended toward the heating presslower part 7, with the result that it rests on the third circular ring 7of the heating press lower part 7. The ring seal 9 at the upper end ofthe third circular ring 7 then provides sealing between the secondcircular ring 24 of the hood upper part 4 and the third circular ring 7of the hood lower part when the second circular ring 24 rests on thehood lower part. A closed, vacuum-tight hood interior space 12 isobtained, while the vulcanization mold is closed only to some extent. Ifthe ring seals 9 are a hose of variable diameter, they are inflated inorder to seal off the hood 4, 7 in a vacuum-tight manner.

FIG. 6 shows the heating press of FIG. 4 and of FIG. 5 in the closedstate after a second partial stroke TH₂. After a vacuum has beengenerated in the interior space 12 of the closed hood 4, 7 of FIG. 5 ,the performance of a second partial stroke TH₂, during which the secondcircular ring 24 is retracted out over the first circular ring 23, thencauses the vulcanizing mold, which has been evacuated of air, to becompletely closed.

FIG. 7 shows a third embodiment of a heating press according to theinvention with a container 2 in the open state. The hood upper part 4has a first and a second circular ring 23, 24, wherein the secondcircular ring 24 is provided with a greater diameter than the firstcircular ring 23. The second circular ring 24 can be telescopicallyretracted and extended on the first circular ring 23 in an axialdirection P1 by means of an actuator 26. The hood lower part 7 has athird circular ring. The diameter of the second circular ring 24 of thehood upper part is slightly less than the diameter of the third circularring 7 of the hood lower part.

The hood upper part 4 and the hood lower part 7 are airtight, orvacuum-tight, and in the closed state form a vacuum-tight hood interiorspace 12. To that end, ring seals 9 are provided. A ring seal 9 isarranged between the first and the second circular ring 23, 24 in agroove 25, which is arranged in the first circular ring 23 and faces thesecond circular ring 24, for an airtight hood upper part 4. Similarly,the third circular ring 23 has a vacuum-tight ring seal 9 around theperiphery on its inner side. Therefore, the closed hood is airtight atthe joints between the hood upper part 4 and the hood lower part 7, andbetween the first and the second circular ring 23, 24. The ring seal 9is a hose of variable diameter. The diameter of the ring seal 9 isslightly greater than the depth 27 of the groove 25 in which it isarranged.

FIG. 8 illustrates the heating press 1 of FIG. 7 in the closing phaseafter a first partial stroke TH₁.

The heating press upper part 3 is moved through the first partial strokeTH₁ and the second circular ring 24 is extended toward the heating presslower part 7, with the result that it rests on the heating press lowerpart 7. The ring seal 9 on the inner side of the third circular ring 7then seals off the small intermediate space between the second circularring 24 of the hood upper part 4 and the third circular ring 7 of thehood lower part when the second circular ring 24 rests on the hood lowerpart. A closed, vacuum-tight hood interior space 12 is obtained, whilethe vulcanization mold is closed only to some extent. If the ring seals9 are a hose of variable diameter, they are inflated in order to sealoff the hood 4, 7 in a vacuum-tight manner.

FIG. 9 shows the heating press of FIG. 7 and of FIG. 8 in the closedstate after a second partial stroke TH₂. After a vacuum has beengenerated in the interior space 12 of the closed hood 4, 7 of FIG. 8 ,the performance of a second partial stroke TH₂, during which the secondcircular ring 24 is retracted out over the first circular ring 23, thencauses the vulcanizing mold, which has been evacuated of air, to becompletely closed.

FIG. 10 shows a fourth embodiment of a heating press according to theinvention with a container 2 in the open state. The embodiment differsfrom the previously described third embodiment merely in that anelastically extensible, vacuum-tight rubber sleeve 28 is provided asadditional vacuum-tight seal between the first circular ring 23 and thesecond circular ring 24 of the hood upper part. This is secured in acircular shape on the inside of the lower part of each of the twocircular rings 23, 24.

FIG. 11 illustrates the heating press 1 of FIG. 10 in the closing phaseafter a first partial stroke TH₁.

The heating press upper part 3 is moved through the first partial strokeTH₁ and the second circular ring 24 is extended toward the heating presslower part 7, with the result that it rests on the heating press lowerpart 7. This causes the rubber sleeve 28, which is fastened to bothcircular rings 23, 24, to extend in the direction of the stroke.

LIST OF REFERENCE SIGNS Part of the Description

-   -   1 Heating press    -   2 Container    -   3 Heating press upper part    -   4 Hood upper part    -   5 Ring seal    -   6 Heating press lower part    -   7 Hood lower part=third circular ring    -   8 Central mechanism    -   9 Ring seal    -   10 Pump    -   11 Vacuum tank    -   12 Interior space of the hood    -   13 Lower heating plate    -   14 Lower sidewall shell    -   15 Upper heating plate    -   16 Upper sidewall shell    -   17 Lower bead ring    -   18 Upper bead ring    -   19 Segment ring    -   20 Segment shoe    -   21 Profile segment/mold segment    -   22 Closing ring    -   23 First circular ring    -   24 Second circular ring    -   25 Groove    -   26 Actuator    -   27 Depth of the groove    -   28 Rubber sleeve    -   TH₁ First partial stroke    -   TH₂ Second partial stroke    -   GH Total stroke

1-12. (canceled)
 13. A heating press for vulcanizing a vehicle tire, thepress comprising: a heating press upper part; a heating press lowerpart; the heating press upper part having a hood upper part mountedthereon and a container, the hood upper part has a first circular ringarranged on the heating press upper part and a second circular ring thatadjoins the first circular ring coaxially in an axial direction, thesecond circular ring configured to be telescopically retracted andextended out over the first circular ring in an axial direction P1; theheating press upper part and the heating press lower part are connectedto the container so when the heating press upper part is lowered througha total stroke (GH) that takes place in the axial direction (P1), duringwhich an open end of the hood upper part moves onto the heating presslower part, mold parts of a vulcanizing mold are closed in a radialdirection (P2); vacuum-tight seals are arranged between the first andsecond circular rings, the second circular ring, and the heating presslower part; the total stroke (GH) can be travelled in a first partialstroke (TH1) and a second partial stroke (TH2); after the first partialstroke (TH1), the hood upper part is moved to rest on the heating presslower part by the second circular ring as extended and an interior spaceof the hood is closed in a vacuum-tight manner by seals although thevulcanizing mold is still open in an air-permeable manner; a pump and avacuum tank to generate a vacuum in the interior space of the hood afterthe first partial stroke (TH1); the hood upper part is moved to permitthe second circular ring to be retracted out further over the firstcircular ring and the vulcanizing mold can be completely closed undervacuum conditions of the interior space of the hood.
 14. The heatingpress of claim 13, further comprising a hydraulic, pneumatic or electricactuator (26), which can move the second circular ring (24) of the hoodupper part (3) in an axial direction (P1).
 15. The heating press ofclaim 13, wherein a hood lower part (7) in the form of a third circularring is arranged on the heating press lower part (6), wherein the firstcircular ring (23) of the hood upper part (3) and the third circularring of the hood lower part (7) have the same inside diameter and thesame outside diameter and are arranged in line with one another in theheating press (1).
 16. The heating press of claim 13, wherein the sealsare ring seals (5, 9), and at least one ring seal (9) is arranged in thelower region of the hood upper part (4) and at least one further ringseal (9) is arranged in the upper region of the hood lower part (7). 17.The heating press of claim 16, wherein the ring seals (5, 9) arearranged in circular-ring-shaped grooves (25), wherein the diameter ofthe ring seals (5, 9) is slightly greater than the depth of the grooves(25).
 18. The heating press of claim 16, wherein the ring seals (5, 9)consist of solid material.
 19. The heating press of claim 16, whereinthe ring seals (5, 9) are hoses of variable diameter.
 20. The heatingpress of claim 16, wherein the ring seals (5, 9) are differentiallyinflated double ring seals.
 21. The heating press of claim 13, whereinsliding bands composed of wear-resistant high-temperature polymer, forexample of PEEK, are arranged in the hood parts (4, 7) in the regionabove and/or below the ring seals (9).
 22. The heating press of claim13, wherein the vacuum tank (11) has a volume that is approximately 5 to10 times greater than the volume of the closed hoods (4, 7).
 23. Amethod for vulcanizing a pneumatic vehicle tire under a vacuum, themethod comprising: a) loading the open heating press (1) by insertingthe green tire for vulcanization into the container (2), wherein thesecond circular ring (24) of the hood upper part (4) is retracted outover the first circular ring (23), b) moving the heating press upperpart (3) through the first partial stroke (TH1), extending the secondcircular ring (24) toward the heating press lower part (6) until itrests on the heating press lower part (6), in order to obtain a closedhood interior space (12), while the vulcanizing mold is only closed tosome extent, c) only if the ring seals (5, 9) are a hose of variablediameter: inflating the circular-ring-shaped hose seal in order to sealoff the hood interior space (12) in a vacuum-tight manner, d) openingthe connection between the vacuum tank (11) and the hood interior space(12) in order to generate a partial vacuum, by way of pressureequalization between the vacuum tank (11) and the hood interior space(12), in the hood interior space (12) that has been closed in avacuum-tight manner, e) when the partial vacuum is obtained in the hoodinterior space (12): closing the connection between the vacuum tank (11)and the hood interior space (12), opening the connection between thehood interior space (12) and the pump (10), and pumping the remainingair out of the hood interior space (12) in order to generate the vacuum,f) moving the heating press upper part (3) through the second partialstroke (TH2), during which the second circular ring (24) is retractedout over the first circular ring (23), with the result that thevulcanizing mold is completely closed, and subsequently closing theconnection between the hood interior space (12) and the pump (10), g)vulcanizing the green tire and opening the connection between the pump(10) and the vacuum tank (11) and generating a vacuum in the vacuum tank(11), wherein the connection of the pump (10) to the hood interior space(12) and the connection of the vacuum tank (11) to the hood interiorspace (12) are each closed, h) opening the heating press (1) andunloading the fully vulcanized tire, and repeating the steps a)-h) inorder to vulcanize each further tire.
 24. The method of claim 23,wherein to facilitate step h), this is preceded by opening a furthervalve arranged in the hoods (4, 7) in order to deplete the vacuum andsubsequently closing it again.